1. The role of Natural History in understanding Speciation and Evolution: Lessons from Lake tana 4 June 2010: Farewell symposium Nand Sibbing Leo A.J. Nagelkerke Aquaculture & Fisheries Group, Wageningen University

4. Birds were my first love Species and Diversity…

5. … Form and Function

6. Why bother about fish when there are birds?

7. Opportunity of a lifetime! © F.A. Sibbing © F.A. Sibbing

8. Lake Tana: source of the Blue Nile

10. The smoking water: Tissisat © F.A. Sibbing

11. State of the art in 1990: only Barbus intermedius

12. But Rüppell (1836) found six species! Eduard Rüppell 1794 – 1884

13. Boulenger (1902, 1911) mentions 10 George Albert Boulenger 1858 – 1937

14. Bini (1940) lists 23 (sub)species

15. What’s the matter with this Barbus intermedius ? © F.A. Sibbing

16. Latest revision: Banister 1973

17. What was measured?

19. Did we do a better job?

21. Labeobarbus species flock

22. Labeobarbus species flock Nagelkerke & Sibbing 1997, 2000: 15 species

23. Did we do a better job? L. dainellii (Bini) L. macrophthalmus (Bini) L. gorguari (Rüppell) L. nedgia (Rüppell) Rüppell and Bini did visit Lake Tana!

24. Many species distinct at small size L. macrophthalmus L. acutirostris L. platydorsus

25. It was not always so clear-cut!

26. Why are we then convinced they are true species?

27. Adaptive radiation as a driver? Form and function Prey pursuit and capture Mechanical breakdown Sorting on taste Sorting on size Prey processing

28. Defining moment 2: Ecomorphology can work!

31. Defining moment 3: You always need a story

32. Biology ≠ Physics Ernest Rutherford (father of nuclear physics): “ All science is either physics or stamp collecting”

33. Biology is a historical science Ernst Mayr (1904 -2005): Evolutionary biology is a historical science … It deals, to a large extent, with unique phenomena , such as … the explanation of organic diversity. Evolutionary biology tries to find the answer to why questions. Experiments are usually inappropriate for obtaining answers to evolutionary questions... There is, however, a remarkably heuristic method available, that of historical narratives . .. so in evolutionary biology you construct a scenario , a historical narrative, which you test for its explanatory value . Hence the ‘History’ in ‘Natural History’

35. Developments in the Eritrean fisheries

36. Artisanal multi-species fisheries

37. Development of fishery

38. Problems with precision of data Species level unreliable: Can we aggregate without losing the relevant signal?

39. Ecological categories in the catches

40. NMDS plots for 1997 based on Bray-Curtis similarities at four levels of aggregation, including species (a), family (b), ecological categories (c) and total catch rates (d) across the six boat–gear combinations. GH: Gillnet–Hook and line; GN: Gillnet; HL: Hook and line. Defining moment 4: You don’t need to know everything

42. Are we teaching the right things?

43. Who will study biodiversity when nobody knows it’s there?

44. Thank you for your attention!